1. Field of the Invention
The present invention relates to drums such as bass drums, snare drums, and marching drums. The present invention also relates to manufacturing methods of cylinders used for drums.
The present application claims priority on Japanese Patent Application No. 2007-63747, the content of which is incorporated herein by reference.
2. Description of the Related Art
Generally, cylinders of drums (or drum shells) having openings, across which drumheads are stretched under tension, are manufactured using wooden materials, metals such as aluminum, and other materials such as fiber-reinforced plastics (FRP). For example, wooden materials having adequate hardness and superior acoustic characteristics such as maple, birch, beech, and bamboo have been used for manufacturing cylinders of drums. Drums whose cylinders are composed of metals and synthetic resins cannot produce warm sounds; hence, wooden materials are mainly used as dominant materials for use in the manufacturing of cylinders of drums.
Conventionally-known examples of drums have been disclosed in various documents, namely, Patent documents 1 to 4 as follows:                Patent document 1: Japanese Unexamined Patent Application Publication No. 2003-316349.        Patent document 2: Japanese Unexamined Patent Application Publication No. H11-45087.        Patent document 3: Japanese Patent No. 3324577.        Patent document 4: Japanese Examined Utility Model Application Publication No. S53-47939.        
Patent document 1 teaches the laminated structure of a drum shell in which a first sheet material having elasticity is adhered to a second sheet material via the adhesive. As the first sheet material, it is preferable to use synthetic composite materials such as polyester films or similar materials. As the second sheet material, it is preferable to use hard phenol resins, epoxy-base resin fibers, boards, and woods.
Patent document 2 teaches a drum whose cylinder is formed in a polygonal prism composed of a wooden material or a non-wooden material. As the wooden material, it is possible to use particle boards, fiber boards, laminated lumbers, laminated woods, plywood, and the like. As the non-wooden material, it is possible to use synthetic resins, glass fibers, carbon fibers, and boron fibers as well as composite materials selectively using them, and the like.
Patent document 3 teaches a drum whose cylinder is formed using a butt board composed of a plurality of thin flat bamboo members whose surfaces and backsides are alternately joined together in width directions. A plurality of butt boards are laminated together to form a plurality of plywood, which are then joined together in width directions, thus forming the cylinder of a drum.
Patent document 4 teaches that elongated thin wooden boards are joined together in a cylindrical shape so as to form a cylinder of a drum.
The drums disclosed in Patent documents 1 to 4 have merits and demerits, so that they have room for further improvements. Specifically, in the drum shell disclosed in Patent document 1, the sheet materials are mainly composed of plastics, which, unlike wooden cylinders, make it very difficult to produce warm sounds. Compared with wooden cylinders, this type of drum cylinder has a low rigidity and is thus elastically deformable due to the tension of a drumhead or snappy members; this may result in poor tuning.
The cylinder of a drum disclosed in Patent document 2 is shaped in a polygonal prism and is composed of a plurality of boards, which are joined together in width directions. This makes it very difficult for the external peripheral portion of a drumhead to be bent along the opening edge of a cylinder; hence, it is necessary to use a special structure for stretching the drumhead. In other words, generally-known head frames (or hoops) are not adaptable to this type of drum.
The drum disclosed in Patent document 3 needs numerous steps for manufacturing bamboo plywood, which thus raises the manufacturing cost.
The cylinder of a drum disclosed in Patent document 4 is formed using elongated thin wooden boards, which are easily deformable due to drying and age degradation, whereby gaps may be easily formed between the elongated thin wooden boards. For this reason, a tightening member such as a belt is wound around the exterior circumference of a cylinder, wherein screws are inserted into holes formed in the cylinder such that the distal ends thereof are connected to the tightening member via nuts, which are appropriately adjusted so as to apply tension to the tightening member. This increases the number of parts and the number of steps in manufacturing, thus increasing the manufacturing cost. It may be possible to reduce the number of elongated thin wooden boards by enlarging their widths; however, it is very difficult to select wooden materials having regular grain in view. This reduces yields in manufacturing and further increases manufacturing costs.